Hydrogen is a very attractive fuel because it is clean and can be used to efficiently produce electricity in a fuel cell. The automotive industry expends significant resources in the development of hydrogen fuel cells as a source of power for vehicles. Such vehicles would be more efficient and generate fewer emissions than today's vehicles employing internal combustion engines.
A hydrogen fuel cell is an electrochemical device that includes an anode and a cathode with an electrolyte disposed therebetween. The anode receives hydrogen gas and the cathode receives oxygen or air. The hydrogen gas is disassociated in the anode to generate free hydrogen protons and electrons. The hydrogen protons pass through the electrolyte to the cathode. The hydrogen protons react with the oxygen and the electrons in the cathode to generate water. The electrons from the anode cannot pass through the electrolyte, and thus are directed through a load to perform work before being sent to the cathode. The work acts to operate the vehicle.
Many fuel cells are typically combined in a fuel cell stack to generate the desired power for the vehicle. The fuel cell stack receives a cathode input gas as a flow of air, typically forced through the stack by a compressor. Not all of the oxygen in the air is consumed by the stack, and some of the air is output as a cathode exhaust gas that may include water as a stack by-product.
The components of the fuel cell system in the vehicle, such as a compressor motor and a compressor motor power inverter module, generate heat during operation of the fuel cell system. The heat energy must be removed from the fuel cell system to keep the internal temperatures of the components and fuel cell system within desired operating conditions to militate against damage to the components. Heat energy is typically removed from the fuel cell system by a coolant caused to flow through the fuel cell system by a recirculation pump. If the recirculation pump fails or the coolant leaks from the fuel cell system, the fuel cell system may overheat, shutdown, and cause the components to perform below an optimal level. Further, if the fuel cell system is shutdown or damaged, an operator of the vehicle incorporating the fuel cell system may not be able to operate the vehicle, resulting in a walk home incident
It would be desirable to provide a method for operating a fuel cell system when the fuel cell system is operating outside of desired thermal operating conditions.